You're feeling under the weather, but is it a cold or the flu? Sometimes it's hard to tell initially, and even more difficult to decide if you should make an appointment with your doctor. One Baylor College of Medicine expert ...

Two drugs used to treat asthma and allergies may offer a way to prevent a form of pneumonia that can kill up to 40 percent of people who contract it, researchers at the University of Virginia School of Medicine have found.

(HealthDay)—This year's influenza vaccine is a fairly good match for the circulating viruses, according to research published in the Feb. 17 issue of the U.S. Centers for Disease Control and Prevention's Morbidity and Mortality ...

A vital race is on in laboratories across the globe to develop a vaccine for the Zika virus. However, even if a vaccine were available today, many of the world's poorest people would not be able to receive it due to political ...

The Advisory Committee on Immunization Practices (ACIP) released its 2017 Recommended Immunization Schedule for adults with major changes to the influenza, human papillomavirus (HPV), and meningococcal (MenB) vaccines. This ...

A steep increase of human cases of avian influenza A(H7N9) has been reported since the beginning of December 2016 from China. During this wave, the number of human cases is already higher than during the last two waves in ...

A study just published in Human Vaccines & Immunotherapeutics suggests that an alternative vaccine might bring clinical benefits and cost savings if used on a large scale when compared to the one currently in widest use.

Influenza

Influenza, commonly referred to as the flu, is an infectious disease caused by RNA viruses of the family Orthomyxoviridae (the influenza viruses), that affects birds and mammals. The name influenza comes from the Italian influenza, meaning "influence" (Latin: influentia). The most common symptoms of the disease are chills, fever, sore throat, muscle pains, severe headache, coughing, weakness and general discomfort. Fever and coughs are the most frequent symptoms. In more serious cases, influenza causes pneumonia, which can be fatal, particularly for the young and the elderly. Although it is often confused with other influenza-like illnesses, especially the common cold, influenza is a much more severe disease than the common cold and is caused by a different type of virus. Influenza may produce nausea and vomiting, particularly in children, but these symptoms are more common in the unrelated gastroenteritis, which is sometimes called "stomach flu" or "24-hour flu".

Typically, influenza is transmitted through the air by coughs or sneezes, creating aerosols containing the virus. Influenza can also be transmitted by bird droppings, saliva, nasal secretions, feces and blood. Infection can also occur through contact with these body fluids or through contact with contaminated surfaces. Airborne aerosols have been thought to cause most infections, although which means of transmission is most important is not absolutely clear. Influenza viruses can be inactivated by sunlight, disinfectants and detergents. As the virus can be inactivated by soap, frequent hand washing reduces the risk of infection.

Influenza spreads around the world in seasonal epidemics, resulting in the deaths of hundreds of thousands annually — millions in pandemic years. Three influenza pandemics occurred in the 20th century and killed tens of millions of people, with each of these pandemics being caused by the appearance of a new strain of the virus in humans. Often, these new strains appear when an existing flu virus spreads to humans from other animal species, or when an existing human strain picks up new genes from a virus that usually infects birds or pigs. An avian strain named H5N1 raised the concern of a new influenza pandemic, after it emerged in Asia in the 1990s, but it has not evolved to a form that spreads easily between people. In April 2009 a novel flu strain evolved that combined genes from human, pig, and bird flu, initially dubbed "swine flu", emerged in Mexico, the United States, and several other nations. WHO officially declared the outbreak to be a "pandemic" on June 11, 2009.

Vaccinations against influenza are usually given to people in developed countries and to farmed poultry. The most common human vaccine is the trivalent influenza vaccine (TIV) that contains purified and inactivated material from three viral strains. Typically, this vaccine includes material from two influenza A virus subtypes and one influenza B virus strain. The TIV carries no risk of transmitting the disease, and it has very low reactivity. A vaccine formulated for one year may be ineffective in the following year, since the influenza virus evolves rapidly, and new strains quickly replace the older ones. Antiviral drugs can be used to treat influenza, with neuraminidase inhibitors being particularly effective.